Architectural heat and moisture exchange

ABSTRACT

An architectural heat and moisture exchanger. The exchanger defines an interior channel which is divided into a plurality of sub-channels by a membrane configured to allow passage of water vapor and to prevent substantial passage of air. In some embodiments, the exchanger includes an opaque housing configured to form a portion of a building enclosure, such as an exterior wall, an interior wall, a roof, a floor, or a foundation.

CROSS-REFERENCES

This application also incorporates by reference in its entirety for allpurposes the following: U.S. Pat. No. 6,178,966, issued Jan. 30, 2001and U.S. Patent Publication No. 2007/0151447 to Merkel, published Jul.5, 2007.

INTRODUCTION

In centrally heated or cooled buildings, fresh air or “makeup air” istypically added continuously to the total volume of circulated air,resulting in some previously heated or cooled air being exhausted fromthe building space. This can result in an undesirable loss of energy andhumidity from the building. Heat exchangers are commonly used in theexhaust air and makeup airflow paths of these systems to recover some ofthe energy from the exhaust air and to induce warmer makeup air duringheating processes and cooler makeup air during cooling processes.

Materials used for heat exchangers commonly include metal foils andsheets, plastic films, paper sheets, and the like. Good heat exchange isgenerally possible with these materials, but significant moistureexchange cannot easily be performed. Desiccants, or moisture adsorbingmaterials, are occasionally employed to transfer moisture. With thismethod, the desiccant merely holds the moisture. To effectively transfermoisture between gas streams, the desiccant must be relocated from thegas stream of higher moisture content to the gas stream of lowermoisture content, requiring an additional input of mechanical energy.With many desiccant materials, satisfactory performance can be achievedonly with the input of additional thermal energy to induce the desiccantto desorb the accumulated moisture.

Heat and moisture exchange are both possible with an exchange film madeof paper. However, water absorbed by the paper from condensation, rain,or moisture present in the air can lead to corrosion, deformation, andmildew growth, and, hence, deterioration of the paper exchange film.

The various types of heat and moisture exchangers in common usage aregenerally contained within an opaque metal housing and located at ornear the building air-handling units in the mechanical room, basement,or rooftop of the building. The nature of moisture exchange requires avery large surface area in contact with the gas stream, and,consequently, so-called total heat exchangers are often very large insize when compared to heat-only exchangers. A larger exchanger in theconventional locations requires additional mechanical room space and/oradditional load-bearing capacity of the roof in the case of a roof-topunit.

Porous polymeric or ceramic films are capable of transferring both heatand moisture when interposed between air streams of differing energy andmoisture states. A system for heat and moisture exchange employing aporous membrane is described in Japanese Laid-Open Patent ApplicationNo. 54-145048. A study of heat and moisture transfer through a porousmembrane is given in Asaeda, M., L. D. Du, and K. Ikeda. “ExperimentalStudies of Dehumidification of Air by an Improved Ceramic Membrane,”Journal of Chemical Engineering of Japan, 1986, Vol. 19, No. 3. Adisadvantage of such porous composite film is that it also permits theexchange of substantial amounts of air between the gas streams, as wellas particles, cigarette smoke, cooking odors, harmful fumes, and thelike. With respect to building indoor air quality, this is undesirable.In order to prevent this contamination of make-up air, the pore volumeof a porous film is preferably no more than about 15%, which isdifficult and expensive to achieve uniformly. Furthermore, a porous filmmade to a thickness of 5 to 40 micrometers in order to improve heatexchange efficiency tears easily and is difficult to handle.

U.S. Pat. No. 6,178,966 to Breshears addressed the shortcomingsdescribed above by describing an improved apparatus for enabling heatand moisture exchange between makeup and exhaust air streams in theheating and air conditioning system of a structure. The apparatusincluded a rigid frame for holding a pair of light transmitting panes,the frame and panes collectively defining an interior cavity within theapparatus. The apparatus could be integrated into the exterior walls ofa building. The light transmitting properties of the panes allowincident solar radiation to permeate the panels, creating a more naturalambient environment in the interior of the structure adjacent with thepanel, as well as raising the temperature of the air stream and thewater vapor permeable barrier to further enhance the exchange ofmoisture through the barrier.

In the prior art Breshears apparatus, a water-vapor-permeable barrierwas provided within the apparatus, to divide the interior of theapparatus into sub-channels for receiving makeup and exhaust airstreams, respectively. The barrier was described as a composite filmmade of porous polymeric membrane having applied thereto awater-vapor-permeable polymeric material so as to form a non-porousbarrier to block the flow of air and other gas.

Despite overcoming some of the shortcomings of preexisting systems, theprior art Breshears apparatus was limited in some ways. For example, thedisclosed apparatus was limited to transparent structures configured tobe integrated into the exterior of a building. Furthermore, thepolymeric membranes described by Breshears were limited to certainparticular membrane materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view depicting an embodiment of a heat andmoisture exchanger (“exchanger”) according to aspects of the presentteachings.

FIG. 2A is a perspective view of another embodiment of an exchangeraccording to aspects of the present teachings.

FIG. 2B is a sectional side view of a portion of the apparatus of FIG.2A.

FIG. 3A is a perspective view of another embodiment of an exchangeraccording to aspects of the present teachings.

FIG. 3B is a sectional side view of a portion of the apparatus of FIG.3A.

FIG. 4 is a perspective view of another embodiment of an exchangerintegrated into an illustrative exterior building wall.

FIG. 5 is a perspective view of another embodiment of an exchangerintegrated into an illustrative building roof.

FIG. 6 is a perspective view of another embodiment of an exchangerintegrated into an illustrative building floor.

FIG. 7 is a perspective view of another embodiment of an exchangerintegrated into an illustrative building foundation.

FIG. 8 is an isometric view of another embodiment of an exchangershowing an illustrative layer of insulation.

FIG. 9 is an isometric view of another embodiment of an exchangershowing another illustrative layer of insulation.

FIG. 10A is a sectional top view of another embodiment of an exchangerintegrated into an illustrative weather-resistant wall layer.

FIG. 10B is a sectional side view of the apparatus of FIG. 10A.

FIG. 11 is a perspective view of another embodiment of an exchangerintegrated into an illustrative building interior wall.

FIG. 12 is a perspective view of another embodiment of an exchangerintegrated into an illustrative building intermediate floor system.

FIG. 13 is a sectional view of the exchanger of FIG. 12, showing theexchanger integrated into an illustrative building underfloor plenum.

FIG. 14 is a perspective view of another embodiment of an exchangerintegrated into an illustrative building intermediate ceiling system.

FIG. 15 is a sectional view of the exchanger of FIG. 14, showing theexchanger integrated into an illustrative building above-ceiling plenum.

FIG. 16 is a perspective view of another embodiment of an exchanger, inwhich a portion of the exchanger is constructed from radiant energytransmitting enclosure material.

FIG. 17 is a sectional view of a portion of the exchanger of FIG. 16.

FIGS. 18-23 are magnified views of a portion of alternative embodimentsof the exchanger of FIG. 16, depicting various types of radiant energyabsorptive elements that may be disposed within the exchanger of FIG.16.

FIG. 24 is a schematic elevational view of an exchanger system, showinghow an exchanger may be coupled with a mechanical cooling andventilation apparatus through a dedicated fluid communication channel.

FIG. 25 is a schematic elevational view of another exchanger system,showing how an exchanger may be coupled with a mechanical cooling andventilation apparatus through a building plenum space.

FIG. 26 is a schematic elevational view of still another exchangersystem, showing another manner in which an exchanger may be coupled witha mechanical cooling and ventilation apparatus through a building plenumspace.

FIG. 27 is a schematic elevational view of yet another exchanger system,showing how an exchanger may be coupled directly with a mechanicalcooling and ventilation apparatus.

DETAILED DESCRIPTION

The present teachings relate to improved methods and apparatus forrecovering energy and/or moisture as air is added to and exhausted froman enclosed space. These teachings may be combined, optionally, withapparatus, methods, or components thereof described in U.S. Pat. No.6,178,966 to Breshears. However, the present teachings expand upon theprior art teachings by disclosing novel improvements such as anexchanger incorporated into an opaque exterior building element. Theseand other aspects of the present teachings are described in detail inthe sections below.

This description discusses some of the basic features of heat andmoisture exchangers according to aspects of the present teachings, andfocuses particularly on incorporating exchangers into various externalbuilding elements, such as walls, foundations, roofs, and slab floorsconfigured to divide an enclosed space from the ambient exterior andcollectively referred to as a building enclosure system. See FIGS.1-10B.

FIG. 1 is a perspective view depicting an illustrative heat and moistureexchanger (which may be referred to herein as simply an “exchanger”),generally indicated at 10, according to aspects of the presentteachings. Exchanger 10 is an apparatus for enabling heat and moistureexchange between air streams. An exchanger housing, generally indicatedat 12, includes an exterior wall 14 defining an interior channel 16through which a gas may pass. A barrier 18 is disposed within interiorchannel 16 and partitions interior channel 16 into sub-channels 20 and22, each of which is adapted to receive a gas stream, such as a sourceair stream A and an exhaust air stream B, respectively. Channel 16, andthus sub-channels 20 and 22, may be in fluid communication with gasstream sources via suitably located openings in housing exterior wall 14such as openings 24 and 26 shown in FIG. 1, which may in turn includelouvers, screens, or other elements configured to direct flow and/orexclude foreign material.

In the embodiment of FIG. 1, exchanger housing 12, and in particularhousing exterior wall 14, is configured to form a substantially opaqueportion of a building enclosure system. Accordingly, exchanger housing12 may be constructed from any suitable, substantially opaque material,such as steel, aluminum or other metal, acrylic, polycarbonate or otherplastic, wood, composites, back-painted or non-transparent glass, orcombinations thereof. Furthermore, the exchanger housing may be sizedand proportioned such that it can be integrated into—and form a partof—a building enclosure. For example, the housing may include astructural frame and enclosing sheet material, and may be configured asa panel forming one or more elements of an overall panelized buildingenclosure system. As described in more detail below, the exchangerhousing may be implemented as a portion of the building wall system,roof system, floor or foundation system, or other part of the building'sexterior.

Barrier 18, which divides interior channel 16 into sub-channels 20 and22, is generally permeable to water vapor and substantially impermeableto the constituent gases of air, which principally include nitrogen andoxygen. Various types of barriers may be suitable for use with thepresent teachings, including microporous polymeric membranes withappropriate characteristics. One particularly suitable type of polymericmembrane is described in U.S. Patent Publication No. 2007/0151447 toMerkel, which is hereby incorporated by reference into the presentdisclosure for all purposes.

In a manner described in more detail below, source and exhaust gasstreams, respectively denoted throughout the drawings as gas stream Aand gas stream B, are directed through adjacent sub-channels 20 and 22within exchanger 10. Due to the proximity of the air streams, heat maybe conducted from the hotter gas stream through barrier 18 and into thecooler gas stream, and moisture may be transported from the gas streamof higher moisture content through barrier 18 and into the gas stream oflower moisture content. Various barrier configurations and resultinggeometries of sub-channels may be chosen depending on the desired heattransfer, moisture transfer, and pressure drop characteristics. Thefollowing paragraphs include descriptions of various such arrangements,with barriers and sub-channels that function in a manner similar tothose described above.

FIG. 2A depicts another illustrative embodiment of a heat and moistureexchanger, generally indicated at 40, according to aspects of thepresent teachings. Pleated-barrier exchanger 40 is similar to exchanger10, including an exchanger housing 42 having a housing exterior wall 44defining an interior channel 46 through which a gas may pass. A barrier48 is disposed within interior channel 46. Unlike the barrier inexchanger 10, barrier 48 is formed in a corrugated or pleated fashion toallow a greater barrier surface area to fit into a given interiorchannel 46, with a corresponding increase in potential moisture and heatexchange. FIG. 2B, which is a sectional side view of the exchanger inFIG. 2A, shows that the folds of barrier 48 may not reach to the innersurface of housing exterior wall 44. Accordingly, a gap may remain oneither side to allow fluid communication within each of two sub-channels50 and 52 formed by the barrier. In other examples, the folds of barrier48 may be configured to contact the inner wall surface of housingexterior wall 44, thus further subdividing sub-channels 50 and 52 into aplurality of smaller sub-channels having substantially triangular crosssections.

FIG. 3A depicts a perspective view of yet another illustrativeembodiment of a heat and moisture exchanger, generally indicated at 80,according to aspects of the present teachings. Multi-barrier exchanger80 is similar to exchanger 10, including an exchanger housing 82 havinga housing exterior wall 84 defining an interior channel 86 through whicha gas may pass. In this example, however, three barriers 88, 90, and 92are disposed in channel 86, forming four sub-channels 94 a, 96 a, 94 b,and 96 b. In this example, gas stream A may flow through sub-channels 94a and 96 a, while gas stream B may flow through sub-channels 94 b and 96b. This flow pattern is more easily seen in the sectional side viewshown in FIG. 3B.

Similar arrangements having odd numbers of barriers with correspondingeven numbers of sub-channels are possible, such as disposing fivebarriers within channel 86 to form six sub-channels evenly dividedbetween gas stream A and gas stream B. Alternatively, some examples mayhave any number of barriers forming any corresponding number ofsub-channels, divided unevenly between gas streams A and B. For example,four barriers may be used to form five sub-channels, with three devotedto gas stream A and two to gas stream B. In yet other examples, thebarrier arrangements of exchangers 40 and 80 may be combined to produceparallel pleated or corrugated barriers, or even alternating corrugatedand flat barriers, in any case forming sub-channels with correspondingshapes.

FIGS. 4-7 depict illustrative exchangers, which may include featuressimilar to those described above, integrated with various aspects of abuilding enclosure system. For simplicity, FIGS. 4-7 are depicted anddescribed below as incorporating exchanger 10 of FIG. 1, but moregenerally, according to the present teachings any of the previouslydescribed exchangers or permutations thereof may be incorporated intoaspects of a building enclosure system.

For example, FIG. 4 is a perspective view depicting an illustrativeexchanger 10 integrated into a building exterior wall 100. As depictedin FIG. 4, a portion of housing exterior wall 14 may be configured toact as an exterior portion of the building enclosure system, and may beexposed to outdoor environmental conditions. Accordingly, at least aportion of housing exterior wall 14 may be constructed ofweather-resistant material. Suitable materials for the housing exteriorwall may include stainless steel; painted, coated, or anodized metal,plastic or wood with coatings or sealants applied to reject moisture andair penetration and retard degradation due to exposure to weather, orother weather-resistant and durable materials. In some examples, aportion of housing exterior wall 14 is exposed to outdoor environmentalconditions while another portion of housing exterior wall 14 is exposedto a building interior. Exchanger 10 may thus form an exterior wallportion and/or an interior wall portion of the building enclosuresystem.

FIG. 5 depicts an illustrative exchanger 10 integrated into a buildingroof 110. As with the exchanger integrated into wall 100, at least aportion of an exterior surface of housing exterior wall 14 may beconfigured to be weather resistant, and may act as a portion of roof110. In the example of FIG. 5, gas streams A and B pass through suitablebuilding exterior openings at the side edge of roof 110, and throughsuitable building interior openings disposed in a ceiling 112 beneathroof 110. Similar to wall integration, exchanger 10 may form an exteriorportion and/or an interior ceiling portion of roof 110.

FIG. 6 depicts a perspective view of another example of an exchanger 10,in this case integrated into an illustrative building floor 120. Asdepicted in FIG. 6, exchanger 10 may act as a portion of floor 120, withsuitable openings for gas streams A and B at a building-interior surfaceof floor 120 and through an exterior wall 100. A portion of housingexterior wall 14 may be configured to act as a portion of floor 120.

FIG. 7 depicts a perspective view of yet another example of an exchanger10, here integrated into a building foundation 130. As depicted in FIG.7, suitable openings in exchanger 10 configured to accommodate gas flowsA and B may be disposed at an outer surface of building foundation 130and at a building-interior floor. In this example, exchanger 10 may forma portion of the outer surface of foundation 130, and may be exposed toexterior environmental conditions. Accordingly, at least a portion ofexchanger 10 may again be constructed of a weather-resistant material.

FIGS. 8 and 9 depict examples of exchanger systems including aninsulation layer 140 that may be disposed adjacent to at least a portionof housing exterior wall 14. In FIG. 8, a single insulation layer 140 isshown adjacent to one side of exchanger 10. In FIG. 9, an alternativeconfiguration is depicted, in which insulation layer 140 surroundsexchanger 10, with openings in layer 140 to allow unhindered passage ofgas streams A and B. These insulation layer depictions are illustrativeonly. Many suitable thicknesses and dispositions of insulation adjacentto exchanger 10 are possible.

FIGS. 10A and 10B depict still another illustrative exchanger system,including an exchanger 10 integrated into a building exterior wall 100.In this example, exchanger 10 may be further integrated into a rainscreen enclosure system. Specifically, rain screen layer 150 may bedisposed on the exterior side of building exterior wall 100, and mayfurthermore leave an air gap 152 between layer 150 and wall 100. FIG.10A is a top sectional view depicting an example of this sort ofarrangement, showing that exchanger 10 may be configured to act as aportion of a rain screen layer 150. As best seen in the sectional sideview of FIG. 10B, a portion of exchanger 10 may also pass through wall100 to allow fluid communication between the external environment andthe building interior for gas streams A and B. To act as a part of therain screen enclosure system, an exposed portion of housing exteriorwall 14 of exchanger 10 may be constructed of weather-resistantmaterial. With layer 150, exchanger 10 may form a continuous layerconfigured to prevent ingress of water into a building.

FIGS. 11-27 depict various other embodiments and aspects of exchangersystems according to the present teachings. More specifically, FIG. 11depicts how an exchanger may be integrated into a building interiorwall; FIGS. 12-13 depict how an exchanger may be integrated into abuilding floor system; FIGS. 14-15 depict how an exchanger may beintegrated into a building ceiling system; FIGS. 16-17 depict how anexchanger may be partially constructed from radiant energy transmittingenclosure material; FIGS. 18-23 depict how various types of radiantenergy absorptive elements may be disposed within an exchanger tofacilitate energy transfer and/or absorption; and FIGS. 24-27 depictvarious ways in which an exchanger may be coupled to a building'smechanical cooling and ventilation apparatus.

The disclosure set forth herein encompasses multiple distinct inventionswith independent utility. While each of these inventions has beendisclosed in its preferred form, the specific embodiments thereof asdisclosed and illustrated herein are not to be considered in a limitingsense as numerous variations are possible. Each example defines anembodiment disclosed in the foregoing disclosure, but any one exampledoes not necessarily encompass all features or combinations that may beeventually claimed. Where the description recites “a” or “a first”element or the equivalent thereof, such description includes one or moresuch elements, neither requiring nor excluding two or more suchelements. Further, ordinal indicators, such as first, second or third,for identified elements are used to distinguish between the elements,and do not indicate a required or limited number of such elements, anddo not indicate a particular position or order of such elements unlessotherwise specifically stated.

1. An apparatus for enabling heat and moisture exchange, comprising: anexchanger housing including an exterior wall defining a channel throughwhich a gas stream may pass; a barrier, permeable to water vapor andsubstantially impermeable to oxygen and nitrogen, disposed within theinterior channel and partitioning the interior channel into a pluralityof separate sub-channels; wherein a first of the sub-channels is adaptedto receive a first gas stream at the same time a second of thesub-channels is adapted to receive a second gas stream; and wherein atleast a portion of the exterior wall forms a substantially opaqueportion of a building enclosure system.
 2. The apparatus of claim 1,wherein at least a portion of the exterior wall of the exchanger housingforms a portion of a wall of the building enclosure system.
 3. Theapparatus of claim 1, wherein at least a portion of the exterior wall ofthe exchanger housing forms a portion of a roof of the buildingenclosure system.
 4. The apparatus of claim 1, wherein at least aportion of the exterior wall of the exchanger housing forms a portion ofa floor of the building enclosure system.
 5. The apparatus of claim 1,wherein at least a portion of the exterior wall of the exchanger housingforms a portion of a foundation of the building enclosure system.
 6. Theapparatus of claim 1, further comprising a layer of insulation disposedadjacent to at least a portion of the exterior wall of the exchangerhousing.
 7. The apparatus of claim 1, wherein at least a portion of theexterior wall of the exchanger housing is exposed to outdoorenvironmental conditions and wherein the exposed portion is constructedfrom a weather-resistant material.
 8. The apparatus of claim 7, whereina first portion of the exterior wall of the exchanger housing is exposedto outdoor environmental conditions and a second portion of the exteriorwall of the exchanger housing is exposed to a building interior.
 9. Theapparatus of claim 7, wherein the exposed portion of the exterior wallof the exchanger housing forms a portion of an outermost layer of a rainscreen enclosure system.
 10. The apparatus of claim 9, further includinga weather-resistant layer separate from the exchanger housing, whereinthe exposed portion of the exterior wall of the exchanger housing andthe weather resistant layer form a continuous layer configured toprevent ingress of water into a building.
 11. An apparatus for enablingheat and moisture exchange, comprising: an exchanger housing defining aninterior channel; a membrane disposed within the housing and dividingthe interior channel into a first sub-channel through which a source gasstream may pass and a second sub-channel through which an exhaust gasstream may simultaneously pass; wherein the membrane is permeable towater vapor and substantially impermeable to constituent gases of air;and wherein at least a portion of the exchanger housing forms asubstantially opaque portion of a building enclosure system.
 12. Theapparatus of claim 11, wherein a portion of the exchanger housing formsan interior wall portion of the building enclosure system.
 13. Theapparatus of claim 11, wherein a portion of the exchanger housing formsan exterior wall portion of the building enclosure system.
 14. Theapparatus of claim 13, wherein the exterior wall portion is exposed tooutdoor environmental conditions and is constructed from aweather-resistant material.
 15. The apparatus of claim 11, wherein afirst portion of the exchanger housing forms an interior wall portion ofthe building enclosure system, and a second portion of the exchangerhousing forms an exterior wall portion of the building enclosure system.16. The apparatus of claim 11, wherein a portion of the exchangerhousing forms a roof portion of the building enclosure system.
 17. Theapparatus of claim 11, wherein a portion of the exchanger housing formsa floor portion of the building enclosure system.
 18. The apparatus ofclaim 11, wherein a portion of the exchanger housing forms a foundationportion of the building enclosure system.
 19. The apparatus of claim 11,further comprising a layer of insulation disposed adjacent to at least aportion of the exchanger housing.
 20. A heat and moisture exchangersystem, comprising: a rain screen layer attached to a building anddefining a gap between the rain screen layer and an exterior wall of thebuilding; an exchanger forming a portion of the rain screen layer andalso passing through the exterior wall to an interior of the building;and a membrane dividing an interior channel of the exchanger into aplurality of sub-channels, the membrane configured to allow passage ofwater vapor and to prevent substantial passage of air; wherein theexchanger is configured (a) to allow passage of a source air stream fromoutside the building, through one of the sub-channels, to inside thebuilding, (b) to allow passage of an exhaust air stream from inside thebuilding, through another of the sub-channels, to outside the building,and (c) to transfer heat and moisture through the membrane between theexhaust air stream and the source air stream.